The present invention is generally directed to thermoelectric materials and methods for their synthesis and, more particularly, to such materials that exhibit enhanced thermoelectric properties.
Solid-state cooling and power generation based on thermoelectric effects are known in the art. For example, semiconductor devices that employ Seebeck effect or Peltier effect for power generation and heat pumping are known. The utility of such conventional thermoelectric devices is, however, typically limited by their low coefficient-of-performance (COP) (for refrigeration applications) or low efficiency (for power generation applications). A thermoelectric figure-of-merit (Z=S2σ/k, where S is the Seebeck coefficient, σ is the electrical conductivity, and k is thermal conductivity) is typically employed as the indicator of the COP and the efficiency of thermoelectric devices. In some cases, a dimensionless figure-of-merit (ZT) is employed, where T can be an average temperature of the hot and the cold sides of the device.
Applications of conventional semiconductor thermoelectric coolers are rather limited, as a result of a low figure-of-merit, despite many advantages that they provide over other refrigeration technologies. In power generation applications, low efficiency of thermoelectric devices made from conventional thermoelectric materials with a small figure-of-merit limits their applications in direct conversion of heat to electricity (e.g., conversion of waste heat or heat generated by specially designed sources).
Accordingly, there is a need for enhanced thermoelectric materials, and methods for their fabrication. More particularly, there is a need for thermoelectric materials exhibiting an enhanced figure-of-merit.